Recreational vehicles are commonly supplied with a retractable awning that extends from a side of the vehicle to provide a quick source of shade. The awnings typically have a rectangular fabric which is attached at one edge to the side of the vehicle and at the other edge to an awning front bar. The fabric may be rolled-up around the front bar and secured to the side of the vehicle when not in use.
The awning front bar, in a basic design, provides a part of a support frame for the leading edge of the fabric and means for attaching a pair of support legs to elevate the awning front bar. A pair of telescoping rafters extends between the ends of the front bar and the vehicle to frame the fabric and space the awning front bar away from the side of the vehicle when the awning is erected. The front bar optionally may be spring-loaded to automatically roll-up the awning fabric when the awning is retracted.
The awning front bar is usually provided with a groove extending lengthwise along the body thereof to receive and retain a bead of fabric formed along the leading edge of the awning fabric to affix the fabric to the front bar. The front bar is commonly adapted at its ends to pivotally mount a pair of telescoping main support legs. The main support legs may be staked into the ground or may be pivotally mounted low along the side of the vehicle.
The awning is erected by pulling the front bar away from the side of the vehicle, which causes the awning fabric to unroll from the front bar. Then the support legs are locked and secured in their fully extended position, and the rafters are extended and attached to the side of the vehicle. The telescoping rafters and supporting legs are commonly provided with locking mechanisms such as spring loaded button locks or threaded locking screws to maintain the support legs and rafters in their extended positions. A variety of awnings for recreational vehicles are disclosed by U.S. Pat. Nos.: 2,432,402; 2,889,840; 3,720,438; 4,117,876; 4,171,013; 4,640,332; 4,719,954; and 4,862,940. The U.S. patents cited thoughout this document are hereby incorporated herein by reference.
U.S. Pat. No. 4,508,126 discloses a telescoping rafter for use with an awning for recreational vehicles. The rafter has three bar-like sections. The outer bar and middle bar are slideably connected by a pin through a slot on the outermost bar. The inner bar and middle bar are connected by a pivot pin that allows these two bars to pivot relative to one another. The rafter further includes a spring housed between the outer bar and middle bar so that when the rafter is pivoted into a fully extended position, the spring is compressed between the outer bar and middle bar telescoping the outer bar to maintain force on the awning fabric.
The Darula U.S. Pat. No. 3,612,145 discloses a telescoping bar used as a support for an awning and having a handle mechanism for telescoping and retracting the bars. As the handle is closed, the rafter lengthens. Once the awning fabric is fully taut, a spring within the rafter is compressed to limit further telescoping of the rafter. The compressed spring also provides a tension locking action.
A common problem with retractable awnings used on recreational vehicles and the like involves providing an awning structure that is easy to erect, yet has rafters capable of maintaining sufficient tension on the awning fabric. To telescope the rafters enough to keep the awning fabric taut requires strength and coordination. It is difficult for one person to exert enough pressure on the rafter to stretch the awning fabric taut and simultaneously extend and lock the rafters into position because of the counteracting force exerted by the fabric. It would be very desirable to provide improved rafters that are easily installed and extended to a locked position and provide sufficient tension to remove undesirable sag from the awning fabric.